Preface: Cloud service providers use “first-to-cache wins” (also known as “cache hit”) for improved performance and efficiency. By caching frequently accessed data, they can quickly retrieve it without needing to access the slower underlying storage layer. This reduces latency, enhances user experience, and can also lower costs associated with accessing and processing data.
Background: In a “first-to-cache wins” scenario, the winning location is in CPU embedded memory, specifically the L1 and L2 caches, which are located directly on the processor chip. The L1 cache is the fastest and smallest, while the L2 cache is slower but larger. Both are much faster than accessing physical memory (RAM).
Do well-known cloud service providers implement the concept of “first-to-cache wins”?
Example 1: S3 is designed to store and manage data objects (files, images, etc.) in the cloud. While S3 itself doesn’t have a “first-to-cache wins” mechanism, it can be used as a layer of caching, especially when combined with other caching services like Amazon ElastiCache for Redis.
Example 2: Google Cloud Storage does not operate on a strict “first-to-cache wins” theory. Instead, it uses a more nuanced caching system that considers factors like the Cache-Control metadata, object type, and the location of the read operation.
Is the Vulnerability Valid?
Yes, it’s valid and serious in the context of build systems that:
-Use remote caching with object storage.
-Allow untrusted contributors (e.g., via pull requests).
-Do not enforce cache validation or isolation between trusted and untrusted environments.
Vulnerability details: A critical security vulnerability exists in remote cache extensions for common build systems utilizing bucket-based remote cache (such as those using Amazon S3, Google Cloud Storage, or similar object storage) that allows any contributor with pull request privileges to inject compromised artifacts from an untrusted environment into trusted production environments without detection. The vulnerability exploits a fundamental design flaw in the “first-to-cache wins” principle, where artifacts built in untrusted environments (feature branches, pull requests) can poison the cache used by trusted environments (protected branches, production deployments). This attack bypasses all traditional security measures including encryption, access controls, and checksum validation because the poisoning occurs during the artifact construction phase, before any security measures are applied.
Official announcement: Please refer to the link for details –